The present invention relates to elastic floor covering boards and to a process for manufacturing such boards. The floor covering boards comprise a lower water-permeable layer of particles of vulcanized synthetic or natural rubber which are bound together by an adhesive, an optional intermediate reinforcing layer and a cover layer of a non-woven fabric or felt of synthetic fibers.
Floor covering boards of this general type which are particularly suitable for surfacing playgrounds and sports fields are known, e.g., from British Patent No. 1,178,949. The manufacture of the known floor covering boards is carried out by blending the rubber particles, which have been freed from fines and dust and which preferably have sizes of from several millimeters up to a few centimeters, with the adhesive in a weight ratio appropriate to provide a water-permeable final layer, placing said impregnated particles into a form and leaving the impregnated particles within the form until the adhesive is cured and a strong bond is obtained. Finally, the cover layer comprising a section of a non-woven fabric or felt is glued to the pre-constructed lower layer of rubber particles.
It has been found that floor covering boards manufactured by such a process have several disadvantages. In particular, thin floor covering boards having exact measurements can be manufactured only with difficulties because it is nearly impossible to place the rubber particles sufficiently uniformly into the form so that a separate layer of rubber particles having an even thickness is obtained. Further, the glueing of the felt layer on top of the pre-formed base layer of rubber particles is difficult because the edges of the felt layer must coincide with the edges of the lower layer and also because the material is subjected to tensions if the adhesive used for the rubber particles is not completely cured, thus causing warps and voids. The adjusting and leveling of the finished floor covering boards by grinding or processing the edges is cumbersome and difficult, in particular if the edges are provided with grooves. Finally, the bond between the lower layer of rubber particles and the cover layer of non-woven fabric or felt is frequently insufficient for the intended use of the boards for surfacing playgrounds and sports fields, and the prior art process is limited to the use of pre-formed webs of non-woven fabric or felt.